httpclient发送Get请求和Post请求

╰半橙微兮° 2023-09-25 12:41 180阅读 0赞

#### 创建HttpClient发送请求、接收响应 ####

*   *  Get请求简介
     *   *  get无参数
         *  get有参数
     *  Post请求简介
     *   *  post携带JSON参数
         *  post携带表单参数
     *  postman自动生成OKhttp代码

### Get请求简介 ###

*  1). 创建HttpClient对象,可以使用`HttpClients.createDefault()`；
 *  2). 如果是无参数的GET请求，则直接使用构造方法`HttpGet(String url`)创建HttpGet对象即可；
 *  3）如果是带参数GET请求，则可以先使用`URIBuilder`(String url)创建对象，再调用`addParameter`(Stringparam, String value)\`， 或setParameter(String param, String）  
    value)来设置请求参数，并调用build()方法构建一个URI对象。
 *  4). 创建HttpResponse，调用HttpClient对象的`execute(`HttpUriRequest  
    request)发送请求，该方法返回一个HttpResponse。调用`HttpResponse的getAllHeaders()、getHeaders(String`  
    name)等方法可获取服务器的响应头；
 *  5）调用`HttpResponse的getEntity()`方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。通过调用`getStatusLine().getStatusCode()`可以获取响应状态码。
 *  6). 释放连接。

**构建一个Maven项目，引入如下依赖**

<dependency>
                <groupId>org.apache.httpcomponents</groupId>
                <artifactId>httpclient</artifactId>
                <version>4.5.8</version>
            </dependency>

#### get无参数 ####

如果是无参数的GET请求，则直接使用构造方法`HttpGet(String url`)创建HttpGet对象即可

/**
     *普通的GET请求
     */
    public class DoGET {
        
        public static void main(String[] args) throws Exception {
        
            // 创建Httpclient对象
            CloseableHttpClient httpclient = HttpClients.createDefault();
            // 创建http GET请求
            HttpGet httpGet = new HttpGet("http://www.baidu.com");
            CloseableHttpResponse response = null;
            try {
        
                // 执行请求
                response = httpclient.execute(httpGet);
                // 判断返回状态是否为200
                if (response.getStatusLine().getStatusCode() == 200) {
        
                    //请求体内容
                    String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                    //内容写入文件
                    FileUtils.writeStringToFile(new File("E:\\devtest\\baidu.html"), content, "UTF-8");
                    System.out.println("内容长度："+content.length());
                }
            } finally {
        
                if (response != null) {
        
                    response.close();
                }
                //相当于关闭浏览器
                httpclient.close();
            }
        }
    }

#### get有参数 ####

如果是带参数GET请求，则可以先使用`URIBuilder`(String url)创建对象，再调用`addParameter`(Stringparam, String value)

public class HttpclientTest {
        
        @Test
        public void httpGet() throws IOException {
        
            // 1.创建httpclient
            CloseableHttpClient httpClient = HttpClients.createDefault();
            //2. 创建HttpGet，设置URL访问地址
            String urlTest = "https://XXXX/XXX/shopping/platformInfo?platformid=7";
            HttpGet httpGet = new HttpGet(urlTest);
            // 3. 请求执行，获取响应
            CloseableHttpResponse response = httpClient.execute(httpGet);
            //解析响应
            if (response.getStatusLine().getStatusCode() == 2000) {
        
                String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                System.out.println(content.length());
            }
            // 4.获取响应实体
            HttpEntity entity = response.getEntity();
            System.out.println(EntityUtils.toString(entity, "utf-8"));
            response.close();
            httpClient.close();
        }

代码中使用的是公司接口，请求URL前缀就XXX表示了，get请求如图所示  
运行结果：我们已经看到get接口成功返回一条数据  
![在这里插入图片描述][d509abd9f1374c29bf2036367e2479a8.png]

### Post请求简介 ###

*  1). 创建HttpClient对象,可以使用`HttpClients.createDefault()；`
 *  2). 如果是无参数的POST请求，则直接使用构造方法HttpPost(String url)创建HttpPost对象即可；
 *  3）如果是带参数POST请求，先构建HttpEntity对象并设置请求参数，然后调用setEntity(HttpEntityentity)创建HttpPost对象。
 *  4). 创建HttpResponse，调用HttpClient对象的`execute`(HttpUriRequest  
    request)发送请求，该方法返回一个HttpResponse。调用HttpResponse的getAllHeaders()、getHeaders(String  
    name)等方法可获取服务器的响应头；
 *  5）调用`HttpResponse的getEntity`()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。通过调用getStatusLine().getStatusCode()可以获取响应状态码。
 *  6). 释放连接。

#### post携带JSON参数 ####

如果是带JSON参数POST请求，先构建`HttpEntity`对象并设置请求参数，因为我们的参数是JSON格式的，需要将请求对象转换成`string`类型的，然后调用`setEntity(HttpEntityentity)`创建HttpPost对象  
首先我们先创建一个请求实体类PostData，代码如图所示

/**
     * @param
     * @author wcy
     * @create 2022/10/15
     * @return
     * @description
     **/
    public class PostData {
        
        private String categoryid;
        private int currentPage;
        private String end_time;
        private int pageSize;
        private int platformid;
        private String start_time;
        private int step_id;
    
        public String getCategoryid() {
        
            return categoryid;
        }
    
        public void setCategoryid(String categoryid) {
        
            this.categoryid = categoryid;
        }
    
        public int getCurrentPage() {
        
            return currentPage;
        }
    
        public void setCurrentPage(int currentPage) {
        
            this.currentPage = currentPage;
        }
    
        public String getEnd_time() {
        
            return end_time;
        }
    
        public void setEnd_time(String end_time) {
        
            this.end_time = end_time;
        }
    
        public int getPageSize() {
        
            return pageSize;
        }
    
        public void setPageSize(int pageSize) {
        
            this.pageSize = pageSize;
        }
    
        public int getPlatformid() {
        
            return platformid;
        }
    
        public void setPlatformid(int platformid) {
        
            this.platformid = platformid;
        }
    
        public String getStart_time() {
        
            return start_time;
        }
    
        public void setStart_time(String start_time) {
        
            this.start_time = start_time;
        }
    
        public int getStep_id() {
        
            return step_id;
        }
    
        public void setStep_id(int step_id) {
        
            this.step_id = step_id;
        }
    }

@Test
        public void httpPost() throws IOException {
        
            // 1.创建httpclient对象
            CloseableHttpClient httpClient = HttpClients.createDefault();
    //         2.创建post对象，设置URL访问地址
            String url = "https://XxX/XxX/shopping/goodsRank";
            HttpPost httpPost = new HttpPost(url);
            CloseableHttpResponse response = null;
            try {
        
                PostData data = new PostData();
                data.setCategoryid("");
                data.setCurrentPage(1);
                data.setEnd_time("2022-11-02");
                data.setPageSize(20);
                data.setPlatformid(1);
                data.setStart_time("2022-11-02");
                data.setStep_id(464);
                String bodyEntity = JSON.toJSONString(data);
                HttpEntity entity = new StringEntity(bodyEntity, ContentType.APPLICATION_JSON);
                httpPost.setEntity(entity);
                //发送post请求
                response = httpClient.execute(httpPost);
                //解析响应
                if (response.getStatusLine().getStatusCode() == 200) {
        
                    //获取响应数据
                    entity = response.getEntity();
                    System.out.println(EntityUtils.toString(entity, "utf-8"));
                }
            }catch (IOException e){
        
               e.printStackTrace();
            }
       }

运行结果：  
![在这里插入图片描述][c72a89054c41485491ab7e47934b77af.png]

#### post携带表单参数 ####

post请求传递参数的形式是将参数放入表单请求体中，然后将表单对象放入请求体中传递。

//1.获得一个httpclient对象
    CloseableHttpClient httpclient = HttpClients.createDefault();
    //2.生成一个post请求
    HttpPost httpPost = new HttpPost("http://www.baidu.com/");
    //3.请求参数添加到请求体中，表单提交
    List<NameValuePair> nvpList = new ArrayList<NameValuePair>();
    nvps.add(new BasicNameValuePair(key, val));
    UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nvps, charset);
    httpPost.setEntity(formEntity);
    //4.执行get请求并返回结果
    CloseableHttpResponse response = httpclient.execute(httpPost);
    try {
        
        //5.处理结果响应体
        HttpEntity entity = response.getEntity();
    } finally {
        
        response.close();
    }

### postman自动生成OKhttp代码 ###

首先在`postman`编写好post请求的URL，请求参数，请求方式，请求头  
![在这里插入图片描述][8e9ddb6ea1b7486097729898d6650990.png]  
点击`sends`按钮右侧的`code`弹窗展示，如图所示  
![在这里插入图片描述][2387c939e50a4d67b220e4955728193e.png]  
框里面的代码就是自动生成的，我们可以复制代码到`idea中，需要在`maven\`装下OKhhtp的依赖  
官网连接：[https://mvnrepository.com/][https_mvnrepository.com]

OkHttpClient client = new OkHttpClient().newBuilder()
                    .build();
            MediaType mediaType = MediaType.parse("text/plain");
            RequestBody body = new MultipartBody.Builder().setType(MultipartBody.FORM)
                    .addFormDataPart("categoryid","")
                    .addFormDataPart("currentPage","1")
                    .addFormDataPart("end_time ","2022-11-01")
                    .addFormDataPart("pageSize","20")
                    .addFormDataPart("platformid ","1")
                    .addFormDataPart("start_time ","2022-11-01")
                    .addFormDataPart("step_id ","464")
                    .build();
            Request request = new Request.Builder()
                    .url("https://XXX/XXX/shopping/goodsRank")
                    .method("POST", body)
                    .addHeader("Cookie", "laravel_session=eyJpdiI6IkRxcWx6M201UHRWMWFWeDY3b0RURmc9PSIsInZhbHVlIjoid0pSM241cmgvRUk5WndHTnc2azlzNFpHVDh6MCt5R1pSV21pQXRPRDB1eEpyMThNZVUrelRKYzJHSVUzNHp3T290RHppOVNvSFZ3Z2VCQ2g4SEFQUjBXSGpRL3VkcUJiRUFzRGc5b21BRnhOUUwzUkNENlhzUEJlVGtWZkhZNGoiLCJtYWMiOiIyYzM1NDhkYzQ0YmZiNjQ5OWIwZjg1NDA3NTYxZTcyM2IyODAxNWI1ZGU4NmEzOTE2YjRmOTBjYzQzMzUyNjY1In0%3D")
                    .build();
            Response response = client.newCall(request).execute();
            System.out.println(response);
        }

OKhttp的语法跟httpclient差不多，都是http工具类

[d509abd9f1374c29bf2036367e2479a8.png]: https://img-blog.csdnimg.cn/d509abd9f1374c29bf2036367e2479a8.png
[c72a89054c41485491ab7e47934b77af.png]: https://img-blog.csdnimg.cn/c72a89054c41485491ab7e47934b77af.png
[8e9ddb6ea1b7486097729898d6650990.png]: https://img-blog.csdnimg.cn/8e9ddb6ea1b7486097729898d6650990.png
[2387c939e50a4d67b220e4955728193e.png]: https://img-blog.csdnimg.cn/2387c939e50a4d67b220e4955728193e.png
[https_mvnrepository.com]: https://mvnrepository.com/